To achieve improvements in basic photographic characteristics such as photographic speed, graininess and pressure resistance of silver halide emulsions and silver halide photographic light sensitive materials, there have been made attempts to provide silver halide grains characterized in halide composition, specifically, iodide distribution within the grain.
U.S. Pat. No. 4,668,614 discloses a technique of double structure grains comprising a high iodide core and a low iodide shell, thereby enhancing sensitivity and graininess. U.S. Pat. No. 4,614,711 discloses a technique of triple structure grains comprising a low iodide core, a high iodide intermediate shell and a low iodide shell, whereby sensitivity, graininess and pressure resistance are enhanced. European Patent 202784B discloses a technique of quadruple structure grains, in which between a high iodide inner shell and a low iodide outer shell, an intermediate shell having an intermediate iodide content is further provided between the iodide contents of inner and outer shells, thereby enhancing the sensitivity/fog ratio and graininess. JP-A 7-244345 (herein the term, JP-A refers to an unexamined and published Japanese Patent Application) discloses a technique of silver halide grains comprising an internal core containing 1 mol % or less iodide, a first covering layer containing 2 to 20 mol % iodide, a second covering layer containing 3 mol % or less iodide and a high iodide phase formed during and after formation of the second covering layer, thereby enhancing pressure resistance, sensitivity, latent image stability and incubation resistance. JP-A 8-314040 and 9-197593 and U.S. Pat. No. 5,728,515 also disclose similar techniques. However, still further enhanced sensitivity, graininess and pressure resistance are desired. Furthermore, these techniques produced problems such as deteriorated sharpness, so that a technique for solving such problems is desired.